In general, sensor-holding lids of a well-known type comprise a base wall which is externally delimited by a circular border, an axial ledge which is integral to the wall and which is provided with a passing hole for housing the sensor, and a cylindrical wall which is provided with a passing hole for housing he sensor, and a cylindrical wall which is transverse to the base wall and which is arranged radially inside the circular border in order to be fixed onto an annular border to the rolling race outside the bearing.
Due to the extremely poor environmental conditions in which the bearing has to operate and which result in the infiltration of liquid via the hole for the sensor into the inside of the bearing itself, the latter is further provided with a waterproof sealing shield which is arrange din a position substantially facing the lid, which is, in turn, provided with one or two passing draining channels which are obtained in proximity to the circular border in order to stop any liquid stagnating between the shield and the lid themselves.
The waterproof shield is, obviously, an additional element which increases the production costs of he wheel bearing, as well as increasing the axial dimensions, and, furthermore, does not completely protect the bearing from any eventual breakage caused by the liquid which, despite the presence of the draining channels, can still stagnate and freeze at low temperatures.